Indwelling catheters are urinary catheters which are designed to be inserted into the bladder of a patient to remain therein for the duration of certain surgical procedures or longer. In acute and chronic surgical and medical conditions, it is desirable to continuously drain the urinary bladder to irrigate the bladder, or to deliver a medicine. For example, it may be desirable to drain the urinary bladder to measure the hourly urinary output which is an important parameter for calculation of the response of the patient to certain medications such as for example, diuretics. The hourly urinary output is also an important indicator of the kidney function in the study of the pulse rate, fluctuations in the blood pressure, and in cardiac monitoring. In comatose patients, the urinary drainage is important as a part of the total assessment of the patient's medical condition.
Thorough drainage of the bladder has been known to expedite the recovery in spinal cord injuries. Additionally, indwelling urinary catheters are indicated for patients suffering from complicated neurological diseases or who may be heavily sedated and unable to empty their bladder.
In prostate surgery, post-operative bleeding is common, and if left unchecked, may lead to formation of blood clots in the bladder. Indwelling urinary catheters are mandatory to ensure the bladder is not filled with clotting blood and to avoid painful conditions, or shock associated with unrecognized clotting of the bladder.
In certain post prostate or bladder surgeries, the urinary bladder should be continuously irrigated with fluid to prevent blood from clotting inside the urinary bladder. Continuous bladder irrigation is achieved using three-way catheters having an inlet for fluid injection and a drainage tube. If delivery of medication to the urinary bladder is needed on a continuous basis, then the urinary catheter is indwelled and remains in the bladder for the entire duration of the treatment.
In chronic medical and surgical conditions, the urinary bladder may have to be drained for weeks, months, or in some cases for life. Examples of such conditions include debilitated patients unable to urinate and when the patient's medical condition prohibits surgical intervention.
A common type of indwelling catheter, known as a Foley catheter, has a balloon attachment at one end. After the Foley catheter is inserted into the urinary tract and arrives in the bladder, the balloon is filled with sterile water so that the filled balloon prevents the catheter from escaping the bladder. Specifically, as presented in FIGS. 1A and 1B, the Foley catheter 10 has a tubular body 12 with a tip 14 at a proximal end 16. Adjacent to the tip 14, there are several holes or openings 18 (usually with 3×5 mm dimensions) for urinary or blood drainage or medication delivery when the catheter is inserted into the bladder.
In the urinary procedure, the catheter in its closed state, shown in FIG. 1A, is inserted through the urinary tract into the bladder, and the urine and/or blood contained in the bladder penetrates through the holes 18 into the channel within the tubular body 12 to be discharged at the main drainage outlet 20. In order to provide retention of the catheter within the bladder, a sterile fluid is delivered to the balloon 22 by a syringe coupled to the injection port 24. The injection port 24 is connected to the balloon 22 through a separate channel 26 extending along the tubular body 12 of the catheter 10. The main drainage outlet 20 is usually connected to a large urine bag (not shown). A valve 28 is provided at the injection port 24 to facilitate the injection of the sterile fluid when the catheter is to be indwelled.
In the indwelling position, shown in FIG. 1B, with the balloon 22 inflated, the catheter remains in the bladder until it is to be removed. For the removal of the catheter from the bladder, the sterile fluid is removed from the balloon 22 by means of the syringe engaged with the injection port 24 through the valve 28. Once the balloon is deflated, and the catheter is transitioned into the “balloon deflated” state, the catheter may be removed.
The urinary Foley catheter has several disadvantages:
1. The balloon near the tip, when filled with water, may weigh 5-50 grams, depending on how many cubic centimeters of water is injected into the balloon. The balloon with such significant weight “sits” on the most sensitive part of the bladder, e.g., the trigone, thus producing discomfort, irritation and pain. The catheter balloon also prevents complete drainage of urine so that there is residual urine in the bladder at all times. This may cause irritation and eventually initiate infection of the bladder.
2. Accidental inflation of balloon inside the urethra (before arriving in the bladder) is an undesirable situation which may cause urethra injury and even partial urethra tear. Partial or complete urethra tear may produce narrowing of the urethra, known as “urethral stricture”, which may need a complicated surgical procedure to rectify the stricture.
In some cases, the balloon may fail to deflate when the catheter is to be removed. The patient in this situation must be subjected to a complicated procedure in order to puncture the balloon inside the urinary bladder.
3. Accidental pulling of the catheter while the balloon is inflated inside the bladder may occur. This is very painful and may lead to the injury of the bladder neck and/or urethra.
4. In order to leave the catheter indwelling, a sterile syringe and a sterile fluid are needed to inflate the balloon. To the contrary, if the catheter is to be removed from the bladder, a sterile syringe is used to withdraw the fluid from the balloon in order to deflate the balloon. The use of the sterile syringe and fluid transfer complicates the procedure.
A catheter called “Comficath” has been developed which is coated with antibiotics, or Silicon. In some catheters, the issue of Latex®, as a source of irritation, has been addressed, and a new generation of rubber Silicon catheters has been developed. In spite of all these innovations, the problems persist, and a catheter free of the above-presented shortcomings associated with the Foley catheter, namely, presence of residual urine, infection, discomfort, malfunctioning and accidental possible injury to the urethra and/or bladder neck, is still needed in the medical field.
Therefore, it is desirable to provide a urinary catheter with an improved retaining mechanism which is free of the problems associated with the inflating/deflating of the balloon wherein there is a long lasting need in the field of indwelling catheters to alleviate the above discussed anomalies.